Automatic lamp control circuits are well known. Typically, a control circuit utilizes a photosensor to sense the ambient light level. The circuit turns the lamp on at night and off during the day. Such automatic control circuits are particularly useful for nightlights, outdoor lights such as street lights, and for lamps that are in inaccessible locations.
While conventional automatic light systems work well for homes and other fixed buildings with good exposure and a ready source of AC power, such systems may be less suitable for travel trailers, motorhomes, and recreational vehicles. For these applications, lamps typically use DC power sources, which is more readily available than AC power sources. Lamps that work from DC power sources are also known. Such lamps are available commercially for applications such as closets, crawl spaces, and tool sheds, which are typically shielded both from outside light and from other light sources such as passing vehicles.
By contrast, travel trailers, motorhomes, and recreational vehicles pose a different set of problems. For these applications, a lamp is frequently located next to a passenger-side door and under an awning. A conventional lamp with photosensor may not operate properly in an under-awning location. In some cases, the awning may block light to the photosensor, causing it to actuate the lamp prematurely. This may cause the lamp to operate during daylight hours.
Another set of problems arise when the lamp itself emits light that is reflected from various surfaces, including the undersurface of the awning, sidewall of the RV or trailer, surfaces of nearby objects, and even from the ground. Particularly if the awning has a shiny or reflective undersurface, reflected light from the lamp may strike the photosensor, shutting down the lamp. This shut-off can occur as a result of reflectance even when ambient light levels are low. Where a lamp with a light sensor is situated under an awning, reflected light from various surfaces can also cause the lamp to cycle on and off without regard to ambient light.
In addition, a typical outside location may be vulnerable to stray light sources such as headlights from passing vehicles or light from the interior of the recreational vehicle or trailer. After dark, opening the door to the trailer or vehicle allows light from the interior to reach the lamp, which may cause the photosensor to shut off the lamp just when light is needed most, such as upon exiting the vehicle. In these circumstances, it is desirable to have a lamp that is sensitive to ambient light, that is not overly sensitive to reflected light, and that will operate without the availability of AC current. In a location with many stray light sources, it may also be useful to be able to override the light sensor circuit.
Accordingly, it is a general object of the present invention to provide a lamp assembly with an automatic control circuit suitable for outside use with a recreational vehicle, travel trailer, motor home, or similar application.
One object of this invention is to have a reliable light fixture which operates automatically in response to the availability of ambient light.
Another object of this invention is to have a lamp that will operate on DC current. A further object of the invention is to have a lamp that will respond to ambient light from an under-awning location where light fixtures are often placed on travel trailers, motorhomes, and recreational vehicles. It is a further object of the invention to provide a manual override for the lamp. It is a still further object of the invention to provide an attractive automatic outside lamp which can be installed and operated in a conventional outside location on travel trailers, motor homes, and recreational vehicles. It is a further object of the present invention to provide an automatically controlled lamp which is simple in construction and easy to use and install in a conventional location.
According to the present invention, these and other objects and advantages are achieved in a lamp assembly. The RV lamp assembly includes a lamp housing enclosing a light bulb connected to an automatic light control circuit. Electrical leads extend through the lamp housing to connect with a power source in the RV or travel trailer. The light control circuit includes a photosensor for controlling the power delivered to the light bulb in response to a sensed ambient light level. A conventional light bulb for use in a conventional outside light fixture may be used. A conventional RV lamp assembly may be modified in accordance with this invention.
Although this invention is described in terms of a light bulb, it will be noted that any appliance or feature that it is desirable to activate in lowered light levels may be substituted for the light bulb and operated on the same principle. A radio or other music source, security device, or sign may be substituted for the light bulb and housing, for example, with substitutions of circuit elements with appropriate power ratings, for example.
In a first embodiment, the lamp includes a photosensor located to the left side of the lamp assembly adjacent to a tiny hole in the lamp housing. The lamp is mounted on a recreational vehicle or the like in the typical location to the left of the door in the passenger side of the vehicle.
According to another aspect of the invention, the photosensor can be mounted on the RV roof and remotely connected to the remainder of the lamp assembly. In this embodiment, it may be desirable to locate the lamp's switching circuits in the RV near the wall switch that is typically provided for an outside light.